A commercial FT slurry reactor can have hundreds to thousands of cooling tubes spanning most of the vertical extent of the reactor, e.g. 75 feet. These cooling tubes will typically be about 3 to 5 inches in diameter.
Reactor cooling tubes are used to generate saturated steam thereby providing cooling of the contents of a slurry reactor. Specifically, saturated steam is produced when preheated boiler feed water is supplied to the cooling tubes. This steam production absorbs the exothermic heat of reaction within the reactor.
The combination of the large number of tubes, their associated weight, the need to supply boiler feed water at one location and to remove steam from another location, leads to a fairly complex reactor design. The design is even more involved and difficult when the need to remove the cooling tubes from the reactor for maintenance is addressed.
The present invention discloses a cooling tube design that addresses these concerns and facilitates the removal of cooling tubes from a reactor, thereby providing a simple construction for a method of cooling tube installation and maintenance.
A variety of Fischer-Tropsch reactor cooling tube designs are known. However, reactor internal details are generally not made public. Most typically employ the generation of saturated steam within cooling tubes.
Maretto and Krishna, “Design and optimization of a multi-stage bubble column slurry reactor for Fischer-Tropsch synthesis,” Catalysis Today, 66 (2001) 241-248, show schematically the arrangement of cooling tubes in a bubble column slurry reactor; see their FIG. 1.
Bhatt et al., “Catalyst and Process Scale-up for Fischer-Tropsch Synthesis,” Symposium on Fischer-Tropsch and Alcohol Synthesis, 1994 Spring ACS Meeting, San Diego, Calif., Mar. 15-17, 1994, show the arrangement of cooling tubes in a reactor cooled by heat transfer oil.
Kolbel and Ralek, “The Fischer-Tropsch Synthesis in the Liquid Phase,” Catal. Rev. Sci. Eng, 21, 225(1980), show the arrangement of cooling tubes in a reactor as well as the supporting equipment needed to provide boiler feed water and to control the generated steam from the system.
An example of an alternate approach is disclosed in U.S. Pat. No. 5,409,960 to Thomas M. Stark which teaches a method for removing heat from a slurry FT hydrocarbon reactor by using pentane in a gas conversion process to absorb the exothermic heat of reaction in the FT process. Pub. 00614864/EP A1 (Thomas Marshall Stark), which published Sep. 9, 1994, discloses a process that consumes a cooling medium, such as pentane, and vaporizes the cooling medium by the exothermic heat of reaction. Said vaporized medium may then be expanded to produce energy, for example, to drive an air plant compressor to produce oxygen for use in the gas conversion process.